HySIL is a new optical design that combines a curved solid lens with a precisely matched immersion fluid into a single, continuous optical system. This allows the immersion fluid to be used not just as a passive medium (as is common practice), but as an active optical component.
Core principle
In conventional light-sheet microscopes, there is a trade-off between resolution, working distance, and cost. High-resolution systems typically require expensive specialized optics (e.g., objectives with very high numerical aperture) that are only suitable for specific sample preparation methods and small samples.
HySIL solves this problem by:
- Combining a relatively simple, curved solid lens (often an inexpensive air lens) with a precisely tuned immersion fluid.
- Selecting and positioning the fluid so that it corrects the optical aberrations of the solid lens while simultaneously increasing the numerical aperture.
- The entire system acts like a single, continuous lens – without sharp transitions or interfaces that scatter or image light.
This allows inexpensive standard lenses to suddenly achieve the resolution and image quality of expensive specialized optics – over larger tissue areas (centimeters instead of millimeters) and with almost all common sample preparation methods.
Practical implementation
The researchers have realized two variants:
- pLSM-SCOPE: A modular add-on device that can be connected to existing light-sheet microscopes.
- Super-SCOPE: A higher-resolution proof-of-concept version.
The system is relatively compact and can also be integrated into new, inexpensive light-sheet microscopes (e.g., the commercially available SLICE).
Advantages at a glance
| Aspect | Conventional systems | HySIL-based systems |
|---|---|---|
| Cost | High (specialized optics) | Significantly lower |
| Resolution | High, but often limited | High over large tissue areas |
| Sample size | Mostly small | Centimeter scale possible |
| Flexibility | Often only for specific media | Works with almost all common preparation methods |
| Scalability | Complex | Simple as a module or in compact devices |
Scientific basis
The refractive index profile is optimized by precisely matching the solid lens and immersion fluid. This reduces optical aberrations (e.g., spherical aberration) and enables better light collection over greater depths. The researchers have demonstrated this both theoretically and experimentally (using density functional theory and practical tests on brains and cancer biopsies, among others).
In short: HySIL turns a "normal" lens + the right fluid into a powerful, high-resolution optical system – without the need for expensive special hardware.
